1. Field of the Invention
The invention relates to semiconductor process, and in particular to a method and structure for preventing bonding pads from peeling caused by plug process.
2. Description of the Prior Art
In the past, when tungsten plug process used for connections between different metal layers had not been introduced into semiconductor process, poor contacts on bonding pads never occurred. As shown in FIG. 1, a structure for manufacturing boding pads without tungsten plug process involved is shown, wherein reference numerals 10, 12, 14, 16 and 18 indicate substrate, polysilicon layer, oxide layer, aluminum layer and passivation, respectively. Since the aluminum layer 16 is directly and firmly connected to the polysilicon layer 12, the bonding pads cannot peel to cause poor contacts as the bonding pads are connected with outside pins.
However, after the tungsten plug process has been introduced into semiconductor process, bonding pads peeling frequently occurs when the bonding pads are connected with outside pins. As shown in FIG. 2, a structure for manufacturing bonding pads with use of tungsten plug process according to the prior art is shown, wherein reference numerals 10, 12, 14, 15, 16 and 18 represent substrate, polysilicon, oxide layer, tungsten plug layer, aluminum layer and passivation. It's obvious from FIG. 2 that the polysilicon layer 12 is indirectly connected to the aluminum layer 16 via the tungsten plug layer 15. Due poor adhesive force between the tungsten plug layer 15 and the polysilicon layer 12, the connection between the tungsten plug layer 15 and the polysilicon layer 12 easily loosens, resulting in bonding pads peeling.